In vertebrate animals, the heart is a hollow muscular organ having four pumping chambers—the left and right atria and the left and right ventricles—each provided with its own one-way valve to ensure that blood does not flow in the wrong direction. The mitral valve is between the left atrium and the left ventricle, the tricuspid valve between the right atrium and the right ventricle, the pulmonary valve is at the opening of the pulmonary artery, and the aortic valve is at the opening of the aorta above the left ventricle. The natural heart valves are each mounted in an annulus comprising dense fibrous rings attached either directly or indirectly to the atrial and ventricular muscle fibers. Each annulus defines a flow orifice.
Various surgical techniques may be used to repair or replace a diseased or damaged valve. Due to aortic stenosis and other heart valve diseases, thousands of patients undergo surgery each year wherein the defective native heart valve is replaced by a prosthetic valve, either bioprosthetic or mechanical.
When the valve is replaced, surgical implantation of the prosthetic valve typically requires an open-chest surgery during which the heart is stopped and patient placed on cardiopulmonary bypass (a so-called “heart-lung machine”). In one common surgical procedure, the diseased native valve leaflets are excised and a prosthetic valve is sutured to the surrounding tissue at the valve annulus. Because of the trauma associated with the procedure and the attendant duration of extracorporeal blood circulation, some patients do not survive the surgical procedure or die shortly thereafter. Due to these risks, a substantial number of patients with defective valves are deemed inoperable because their condition is too frail to withstand the procedure. By some estimates, about 30 to 50% of the subjects suffering from aortic stenosis who are older than 80 years cannot be operated on for aortic valve replacement.
Percutaneous and minimally-invasive surgical approaches, some of which avoid cardiopulmonary bypass altogether in “beating heart” procedures, are garnering intense attention. Although these remote implantation techniques have shown great promise for treating certain patients, replacing a valve via surgical intervention and bypass is still the preferred treatment procedure. One hurdle to the acceptance of remote implantation is resistance from doctors who are anxious about converting from an effective, if imperfect, regimen to a novel approach that promises great outcomes but is relatively foreign. In conjunction with the understandable caution exercised by surgeons in switching to new techniques of heart valve replacement, regulatory bodies around the world are moving slowly as well.
Accordingly, there is a need for a prosthetic valve that can be surgically implanted in a body channel in a more efficient procedure so as to reduce the time required on extracorporeal circulation. One solution especially for aortic valve replacement is provided by the Edwards Intuity valve system available from Edwards Lifesciences of Irvine, Calif. Aspects of the Edwards Intuity valve system are disclosed in U.S. Pat. No. 8,641,757 to Pintor, et al. The Edwards Intuity valve is a hybrid of a surgical valve and an expandable stent that helps secure the valve in place in a shorter amount of time. The implant process only requires three sutures which reduces the time-consuming process of tying knots. A delivery system advances the Edwards Intuity valve with the stent at the leading end until it is located within the left ventricle, at which point a balloon inflates to expand the stent against the ventricular wall. The long handle and delivery system design facilitate access through smaller incisions (mini-sternotomy or right anterior thoracotomy) than with conventional full sternotomies.
There remains a need for further innovative approaches like the Edwards Intuity valve system that combine the proven effectiveness of existing surgical valves and shorten the implant procedure time.